Wind selectivity of migratory flight departures in birds

Optimal migration theory predicts that birds minimizing the overall time of migration should adjust stopover duration with respect to the rate of fuel accumulation. Recent theoretical developments also take into account the wind situation and predict that there is a time window (a set of days) during which birds should depart when assisted by winds but will not do so if there are head winds. There is also a final day when birds will depart irrespective of wind conditions. Hence, the wind model of optimal migration theory predicts that birds should be sensitive to winds and that there should be a correlation between departures and winds blowing towards the intended migration direction. We tested this assumption by tracking the departures of radio-tagged passerines during autumn migration in southern Sweden. Our birds were moderately to very fat when released and therefore energetically ready for departure. There was a significant correlation between direction of departure and wind direction. We also found that during days when birds departed there was a significantly larger tail wind component than during days when birds were present but did not depart. Our results show that passerines do take the current wind situation into account when departing on migratory flights. We also briefly discuss possible clues that birds use when estimating wind direction and strength. The inclusion of wind is an important amendment to optimal migration theory of birds and should be explored further. Received: 1 March 1999 / Received in revised form: 4 October 1999 / Accepted: 16 October 1999     

The role of perceived government style in the facilitation of self-determined and non self-determined motivation for pro-environmental behavior

Most North Americans are concerned about the environment and feel that responsibility for its protection lies primarily with government; however, no research to date has examined the influence of the government's approach toward environmental regulation on the motivation of individual citizens. According to self-determination theory, social contexts that support one's autonomy should facilitate self-determined motivation and social contexts that thwart autonomy should lead to non self-determined motivation and a sense of apathy or amotivation. In this study (n = 283), we examined the influence of perceptions of the government's approach toward environmental regulation on motivation toward the environment and frequency of self-reported pro-environmental behavior (PEB). Using structural equation modeling, we tested the hypothesis that frequency of PEB is predicted by motivation toward the environment and that motivation is predicted by the extent to which individuals perceive the government to be autonomy-supportive versus controlling in the implementation of environmental policies. The analysis revealed that perception of government autonomy-support contributed positively to autonomous motivation and negatively to amotivation, while perception of government control was positively related to both controlled motivation and amotivation. As predicted, autonomous motivation was positively, and amotivation was negatively, associated with frequency of PEB.     

Effects of organic matter on phosphorus release kinetics in different trophic lake sediments and application of transition state theory

Sediments have a significant influence on the overlying water, and phosphorus (P) release from sediments is an important source for the lake eutrophication, particularly in shallow ones. In this study, effects of organic matter on P release from sediments in different trophic lakes from the middle and lower reaches of Yangtze River, China, were investigated, and the release kinetics of different P fractions at different temperature were studied. The results show that the release kinetics of soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP) and dissolved total phosphorus (DTP) were similar for the studied sediments, the release rate increased rapidly in the initial hours, and it increased gradually after 10h. The release kinetics of SRP, DOP and DTP followed the Power Function model. SRP was the major fraction among the released DTP, while DOP was an important fraction in the heavily polluted sediments. Organic matter restricted the SRP and DTP release while it promoted the DOP release. Both DOP and SRP release processes were endothermic. The thermodynamic properties in the P release kinetics were calculated and discussed.     

浅谈循环经济与畜禽粪便资源化

我国畜禽养殖业发展迅速,但由于相关政策脱节、缺乏合理规划与布局、技术研究落后等原因,畜禽废弃物未经有效处理直接排入环境中,造成毒化水源、污染大气、传播病菌、危害农田等一系列危害.运用循环经济理论指导畜禽粪便环境污染治理,使其实现减量化、资源化、无害化,具有很大的经济效益和环境效益.     

韧性理论视角下贫困村灾后恢复重建与灾害风险管理刍议

韧性理论引入灾害风险管理领域,为世界防灾减灾实践提供了新理念,并在国内外韧性城市社区建设中得到广泛应用,但针对乡村地区,尤其是高脆弱性的贫困村韧性社区建设的研究还较为鲜见.该文以韧性理论为基础,结合乡村振兴战略规划,通过对贫困村社会生态系统特征的分析,探讨了新时期我国贫困村灾后恢复重建与灾害风险管理发展方向及特点.研究...     

电梯困人应急救援理论的初步建立

针对备受社会关注的电梯困人应急救援的快速实现,在电梯应急救援体系建设下,研究电梯困人救援的快速实现的影响因素、改进措施及标准化电梯困人应急救援体系的建立,提出了一种建立标准化电梯困人应急救援体系的理论,该理论在提升电梯应急救援效率,缩短电梯困人救援时间上给出了指导性理论,通过以某医院为实施对象进行了试验数据采集、统计与...     

资源性供给紧约束条件下的消费理论研究述评

通过对国内外关于资源性供给紧约束条件下的消费理论研究的文献回顾,认为在资源环境问题日益严峻的现代社会,深入分析和探寻人与自然和谐共处的居民消费行为,客观上要求我国必须从伦理学、社会学、生态学和法学等多学科领域进行探讨和研究,而不能仅局限于经济学学科研究领域。加快构建生态文明型消费模式,不仅是目前消费理论创新研究的重要方向,而且也是我国贯彻落实科学发展观,实现人口消费与社会、经济、资源和环境全面协调可持续发展的必然选择。     

环境污染源监测中的警示性分析

利用概率论有关知识,对污染源监测数据进行处理、分析、建立数字模型。依该模型可即时捕捉发生环境污染的警示性信号。     

突变理论在环境预测中的应用

以某市七年来环境治理投资状况为序列建立多项式预测模型 ,尽管其拟合精度较高 ,但其预测结果偏离现实情况较大 ,通过突变理论分析知其原因在于有突变因素存在之故     

比较中审视:豫皖苏黄泛区问题研究现状与展望

豫皖苏黄泛区作为黄河距今最近的一次大泛滥产物,对此问题的研究一波三折,先后经历不同时期的低谷与高潮。至今的研究成果主要表现出四个特点：一是研究成果日益丰硕;二是研究领域渐趋平衡;三是创新研究有待加强;四是比较研究稍显不足。同时,在研究黄泛区问题时存在不同程度的理论缺失现象,理论的缺失限制了研究者们的视野和研究的进一步深入。而史料的匮乏也束缚了学者们的手脚,因此,继续挖掘史料成当务之急。研究视角的转换与多学科之间的交流还要进一步加强。